No Caulking??

If a plumbing vent's instructions advise against using caulk, but you still need to seal exposed nails, consider using a roofing cement or sealant specifically designed for roofing applications, as they are often more durable and resistant to weather elements than general-purpose caulk.

It does not mean skip this step.. the inscription does not mean leave nails exposed, it means the flashing itself does not need caulking.